This invention pertains to a fluid motivated pump that may be used in locations where either it would be preferable not to use a pump having an electric motor or electricity is unavailable. A fluid motivated pump of the present invention may be used with food preparation equipment, wastewater equipment and a unit that separates a mixture of insoluble or immiscible fluids into its parts. For example, when used with food preparation equipment, a pump may deliver a grease/water mixture to a separator unit, a gray water part from the separator to a sewer line, and a grease part from the separator to a storage vessel.
Certain locations are hazardous because the atmosphere does or may contain gas, vapor or dust in explosive quantities. The National Electrical Code (NEC) divides these locations into Classes and Groups according to the type of explosive agent that may be present. Methane produced during sewage digestion in a wastewater treatment operation is a Class I, Group D atmosphere. Sparks or flames from a non-hazardous location electrical motor may ignite the methane and cause an explosion. A hazardous location electrical motor designed to withstand an internal explosion of methane, and not allow the internal flame or explosion to escape should be used. Two types of hazardous location electrical motors include a totally enclosed, fan-cooled electrical motor that has an external cooling fan and a totally enclosed, nonventilated, electrical motor that depends on convection for air cooling. A non-electrical alternative would be desirable.
Also, electrical current leaking into water presents a hazard. For example, a unit used to separate a grease/water mixture into a gray water part and a grease part may include one or more pumps. A first pump may be used to transmit the grease part to a storage vessel. A second pump may be used to deliver the gray water part to a sewer line. To satisfy electrical codes, a ground-fault interrupter must protect the electrical lines to the motor of each pump. Watertight electrical boxes may also be required. The electrical lines should be either Type TW wires encased in metal or plastic conduit or Type UF (underground feeder) cable. These precautions are required to prevent electrical shock. Again, a non-electrical alternative would be desirable.
Submerged pumps can be even more challenging. For certain equipment, it is desirable to include a pump within the equipment. A reason may be esthetics. Another reason may be function. No matter the reason, a pump may be submerged in a reservoir of a water-based fluid. To prevent electrical current leakage, the pump, the electrical motor and wiring must be watertight. In a new pump installation, new and clean parts help water tightness; however, the upkeep of the electrical motor and wiring becomes a challenge over time because of the nature of the water-based fluid. If a grease/water mixture is involved, the grease bonds to the electrical motor casing and wire insulation over time. Also, the grease can hold bits of food and other debris and bond these to the motor and wiring insulation. The constant contact of grease and debris with wire insulation, wire conduit and materials for making watertight seals can rot them, leading to electrical current leakage. Also, replacing rotted parts is nasty. The built-up grease must be removed to create clean surfaces. During cleaning, the built-up grease clings to tools and clothing. A large amount of clothing and cleaning rags is thrown out after becoming fouled with grease. Again, a non-electrical alternative would be desirable.
It is apparent that there is a need for a pump that uses a motive method other than an electrical motor. It is also apparent that there is a need for a pump that reduces or eliminates explosion hazards and electrical current leakage hazards.
A pump according to the present invention conveys or pumps a fluid (later called a stock fluid) through a motivating fluid provided at a preselected pressure acting against a movable biasing boundary. A pump according to the present invention includes at least one unit having a cavity in fluid communication with at least one valve and at least one additional valve. The at least one valve regulates the providing and discharging of the motivating fluid while the at least one additional valve regulates the drawing or suctioning and discharging of a stock fluid. The movably biasing boundary splits the cavity into a stock-fluid cell and a motivating-fluid cell. Walls of the cavity and at least a portion of the movable biasing boundary define each cell. A motivating-fluid port is in fluid communication with the at least one valve and the motivating-fluid cell. A stock-fluid port is in fluid communication with the at one additional valve and the stock-fluid cell.
In a first embodiment, the movable biasing boundary comprises a piston movably disposed within the cavity and a biasing element, such as, a spring, acting on the piston and against the pressure of the motivating fluid. The biasing element may be internal to and/or external to the unit. When external to the unit, the biasing unit may act on the piston through a link. A piston may include a seal at its perimeter contacting the cavity walls to prevent the contamination of the motivating fluid by the stock fluid and vice versa.
A pump according to the present invention conveys or pumps at least one stock fluid by directing a motivating fluid through the at least one valve, into the motivating-fluid cell to act on the movably biasing boundary. This action expands the motivating-fluid cell, contracts the stock fluid cell and balances the preselected pressure of the motivating fluid. The at least one valve is then actuated so that the motivating fluid is discharged from the motivating-fluid cell as it contracts through the relaxation of the movably biasing boundary. Concurrently, the stock-fluid cell expands to draw the stock fluid through the at least one additional valve and into the stock fluid cell. The at least one valve and at least one additional valve are actuated to again direct motivating-fluid into the motivating-fluid cell, contract the stock-fluid cell and convey or pump the stock fluid through the at least one additional valve. The repeated alternating between expanding and contracting of the stock-fluid cell conveys the stock fluid. The repeated alternating to convey the stock fluid occurs by the coordinated actuation of the at least one valve and the at least one additional valve. A controller may be used to coordinate the actuation.
In another embodiment, the at least one valve comprises a solenoid actuated valve having two alternative paths. The at least one additional valve comprises two check valves, more preferably, duckbill check valves. One check valve is directed to permit stock fluid to be drawn into the stock-fluid cell during its expansion; the other check valve is directed to permit stock fluid to be conveyed or pumped from the stock-fluid cell during its contraction.
A pump according to the present invention may include a plurality of units or convey a plurality of stock fluids or both. When at least two units are paired, their movable biasing boundaries may be coupled so that they act in opposition, eliminating the need for other biasing components like springs. This provides additional operating and space saving advantages.
A pump according to the present invention uses a fluid as the motive force, eliminating the need for an electrical motor. In this manner, a pump according to the present invention reduces or eliminates explosion hazards and electrical current leakage hazards. In this vein, a pump according to the present invention may be used, for example, in commercial food preparation operations, in wastewater operations, and any other suitable operation that would be apparent to one skilled in the art.
Most preferably the motive fluid is a municipal or other convenient water supply, delivered at its conventional pressure.